The technical field of this invention is motor vehicle traction control, and particularly to its use in vehicles on racetracks.
Vehicle traction controls are used to sense driven wheel slip under powered (non-braking) conditions and control one or both of the vehicle brakes or engine to spin down the driven wheels as necessary to regain traction. But a vehicle involved in high performance operation on a racetrack may lose traction when in a high acceleration state or during gear shift when the new gear is engaged. The wheel spin-up activates the traction control system, which causes a reduction in engine power or a brake activation of the spun-up wheel that reduces vehicle performance at a time when it is most demanded. It is undesirable to merely retune the traction control system to ignore the spin-up, because the action of the traction control system is desirable to handle identical spin-ups encountered in non-controlled maneuvers, particularly in vehicles that may also be operated in normal, off-track driving.
The apparatus of this invention provides traction control for a vehicle by sensing vehicle speed, the rotational speed of a driven wheel, vehicle longitudinal acceleration; vehicle engine speed, vehicle turn curvature, and a currently used gear of the transmission and increasing the predetermined target delta speed value of the traction control when all of the following are true:
(1) the sensed vehicle speed is within a predetermined speed range corresponding to near maximum engine speed for the sensed currently used gear of the transmission;
(2) the sensed vehicle turn curvature is within a predetermined curvature range of zero curvature;
(3) the sensed vehicle longitudinal acceleration has not been below a predetermined high acceleration for a first predetermined time; and
(4) the sensed vehicle engine speed has not been below a predetermined high engine speed for a second predetermined time.
The tests described above are calibrated to provide the increase in a very narrow range of conditions corresponding to high performance operation, and particularly power shifts of a manual shift transmission, on a racetrack with a high coefficient surface.